Analytical apparatus

ABSTRACT

APPARATUS SUITABLE FOR LOADING LIQUID SAMPLES ONTO AN ANALYTICAL DEVICE SUCH AS A CHROMATOGRAPHIC COLUMN. THE APPARATUS HAS A ROTATABLE BARREL CONTAINING CHAMBERS WHICH ARE FILLED WITH LIQUID, AND A GENEVA MECHANISM TO CONTROL ROTATION OF THE BARREL.

NOV. 23, 1971 G GOODMAN ETI'AL 3 62lJ19 ANALYTICAL APPARATUS Filed Nov. 4, 1969 5 Sheets-Shoot 2-1 NOV. 23, 1971 GOODMAN ETAL 3,621,719

ANALYTICAL APPARATUS Filed Nov. 4, 1969 3 Shcats-Shcct Z5 United States Patent 3,621,719 ANALYTICAL APPARATUS Geoffrey Willoughby Goodman, 105 Banstead Road 5.,

Sutton, England, and Lawrence Harvey, Highland Cottage, Cold-Harbour, near Dorlring, England Filed Nov. 4, 1969, Ser. No. 873,940 Claims priority, application Great Britain, Nov. 14, 1968, 53,989/ 68 lint. Cl. @0111 1/00 11.5. H. 73422 Gt: Claims ABSTRACT OF THE DISCLOSURE Apparatus suitable for loading liquid samples onto an analytical device such as a chromatographic column. The apparatus has a rotatable barrel containing chambers which are filled with liquid, and a Geneva mechanism to control rotation of the barrel.

The present invention relates to apparatus for automatic loading of liquid samples of accurately known volume onto an appropriate device for example an analytical device such as a chromatographic column.

According to the present invention, apparatus suitable for automatically loading liquid samples onto an analytical device comprises a rotatable barrel having a plurality of chambers whose axis is parallel to the axis of rotation at constant interval and radius, sandwiched between two members each of which has a port in its face which is the termination of a conduit, wherein the barrel occupies positions in which a chamber in the barrel aligns with the ports in the members to give a continuous passage, a Geneva mechanism and motor to rotate the barrel, and a time to actuate the motor and drive the Geneva mechanism to cause rotation of the barrel.

In operation liquid is passed from a suitable source, through the members, which may be discs, and rotatable barrel, to a receptacle. By rotating the barrel through one interval, the amount of liquid in the chamber in the rotatable barrel is trapped between the discs while another chamber in the barrel completes the passage from liquid source to receptacle. Each chamber in the barrel may be filled in this Way, the size of each sample being accurately known from the volume of the chamber in the barrel. When the barrel is loaded, the samples may be transferred to a receptacle, for an example a chromatographic column, by aligning a loaded chamber between the conduits in the two discs. A suitable fluid is passed through the continuous passageway to wash the contents of the chamber onto the chromatographic column. The timer is set to actuate motor and Geneva mechanism and cause rotation of the barrel at fixed time intervals. When this occurs a fresh sample is inserted in the path of the fluid and an accurately known volume is passed onto the column. The number of samples which may be automatically processed before the barrel has to be reloaded depends of course on the number of conduits in the barrel.

It is essential if the samples taken and delivered are to be of constant size that the conduits in the barrel align exactly with the conduits in the discs. For this reason 2. Geneva mechanism, which will permit rotation only over a constant interval which may be very accurately determined is used to control rotation.

To ensure that there is no leakage of sample the discs and the rotatable barrel must fit together very closely, and it is preferred that their faces are optical flats, which are preferably urged together by a spring. A suitable material from which the discs and barrel may be made is stainless steel, but different grades should be used for surfaces which are in contact, so that they will not weld together. In an alternative embodiment the faces may have inserts of a self lubricating material, such as Teflon.

When used with a chromatographic column, the timer is preferably used to put a mark on a recorder trace, which may be obtained from the column via an auxiliary circuit, for example, at the same time as the barrel is rotated so that the admission of a new sample to the column is recorded.

The invention is further illustrated in the accompanying drawings:

FIG. 1 shows a sectional elevation of the apparatus FIG. 2 shows a plan view showing the Geneva mechanism more clearly FIG. 3 is a sectional elevation of part of the apparatus showing the Geneva mechanism more clearly.

A stainless steel rotatable barrel 1 made of one grade of stainless steel is sandwiched between two discs 2 and 3 of a different grade of stainless steel. The rotatable barrel is keyed into a spindle 4 which in turn is attached to a gear wheel 5 which engages with a gear wheel '6 which is controlled by the Geneva mechanism.

The rotatable barrel has a plurality of chambers of which two, 7 and 8 are shown. The chamber 7 is aligned so that it forms a continuous passage with conduit 9 in disc 2 and conduit 10 in disc 3. Disc 2 has a projection 11 which is shaped to fit into the top of a chromatographic column (not shown). A spring 12 urges the discs 2 and 3 and the rotatable barrel 1 into close contact, the spring being supported by a backing plate 13.

A 30 rpm. synchronous motor, 14, started by a short electric pulse originating from a Crouzet synchronous timer 113H rotates a spindle 15 and an attached gear 16 one turn only being then switched off by a microswitch (not shown) on a cam on 15. Gear 16, which is part of a 6 point Geneva mechanism, rotates gear 17, the other part of the Geneva mechanism, by 60 precisely. Reduction gears 6 and 5 convert this rotation to one of 30 on the rotatable barrel, moving conduit 7 out of alignment with conduits 9 and 1t] and bringing another into alignment with them. Liquid is passed through conduits 9 and 10 and whichever chamber is in alignment with them. When the barrel is rotated the contents of the chamber 7 are trapped. When it is desired to pass the contents of chamber 7 onto the chromatographic column, it is moved into alignment again with conduits 9 and 10 and an inert solvent is passed through the passage to wash the contents of chamber 7 onto the column.

We claim:

1. Apparatus for receiving and storing a plurality of liquid samples and for supplying said samples to an analytical device, said apparatus comprising a rotatable barrel having a pir of oppositely facing surfaces extending substantially perpendicular to the axis of rotation of said barrel and spaced from each other in the direction of said axis and having a plurality of liquid-tight chambers extending therethrough from one said surface to the other surface thereof and in a direction parallel to the axis of rotation of said barrel, said chambers being spaced at equal distances from said axis of rotation and being regularly spaced from each other around said axis, a pair of members mounted on axially opposite sides of said barrel and each having a single port with a fluid conduit leading thereto which is spaced from said axis a distance substantially equal to the spacing of said chambers from said axis, one of said members being mounted with a face thereof in liquid-tight contact with said one surface and covering said chambers except at the portion thereof containing said port therein and the other of said members being mounted with a face thereof in liquid-tight contact with said other surface and covering said chambers except at the portion thereof containing said port therein and being mounted with its port in axial alignment with the port in said one member, whereby when one said chamber is aligned with said ports, liquid is permitted to flow from one said port to the other said port through said one chamber and the other chambers are sealed against removal of liquid therefrom, and means for periodically rotating said barrel by fixed predetermined amounts which cause each chamber to become successively aligned with said ports, said rotating means comprising a motor interconnected with said barrel by a Geneva mechanism and a timer for periodically energizing said motor, whereby, when said barrel is rotated, liquid in said chambers is trapped and retained and upon further rotation the liquid is withdrawn serially from each chamber through a port into the analytical device.

2. Apparatus according to claim 1 wherein all of said chambers have the same volume.

3. Apparatus according to claim 1 wherein the membars are discs and the faces of the discs and the surfaces of said barrel are urged together by a spring.

4. Apparatus according to claim 1 wherein the surfaces of said rotatable barrel and the adjacent faces of said members have inserts of a self-lubricating material.

5. Apparatus according to claim 1 wherein the timer marks a recorder, as the barrel is rotated, to record the admission of a new sample to the recorder.

References Cited UNITED STATES PATENTS 2,757,541 8/1956 Watson et a1. 73-Z3.1 X 2,830,738 4/1958 Sorg et a1. 73422 3,081,158 3/1963 Winter 73423 X 3,285,054 11/1966 Heller 7323.1

FOREIGN PATENTS 1,091,193 11/1967 Great Britain 73422 LOUIS R. PRINCE, Primary Examiner W. A. HENRY, Assistant Examiner 

